Dry mounting press

ABSTRACT

The invention is an improved press for dry mounting photographic prints and the like to a supporting substrate. The press comprises a bed, a heated platen assembly hinged with respect to the bed, and a cross-bar assembly that supports the platen assembly and comprises adjustable means for transmitting closing pressure to the platen assembly at selected points. The platen assembly also is constructed so as to provide a more uniform heating of the work.

United States Patent 1191 Humphries Dec. 2, 1975 [541 DRY MOUNTING PRESS2,644,151 6/1953 Krueger 156/366 3,450,032 6/1969 Van Hartesveld et al100/93 P [75] Inventor: 2 Humphnes, Oxford 3,617,696 11/1971 Reenstra Ctal 219/243 onn.

[73] Assignee: Seal Incorporated, Derby, Conn. Primary Examiner-CharlesE. Van Horn Assistant ExaminerJ. J. Gallagher [22] Flled' May 1973Attorney, Agent, or Firm-Schiller & Pandiscio [2]] Appl. No.: 359,909

[57] ABSTRACT [52] US. Cl 156/580; 100/93 P; 1251647223; The inventionis an improved press for y mounting [51] Int Cl 2 B30B 15/34photographic prints and the like to a supporting sub- [58] i P 99 93strate. The press comprises a bed, a heated platen as- 156/583 367 380sembly hinged with respect to the bed, and a cross-bar assembly thatsupports the platen assembly and comprises adjustable means fortransmitting closing pres- 219/243 34/143 16/2 403/118 29/238 sure tothe platen assembly at selected points. The [56] Refere Ce Cted platenassembly also is constructed so as to provide 21 UNITED STZTES ATENTSmore uniform heating of the work. 921,067 5/1909 Bentley 34 143 14Claims, 16 Drawing Figures E F I 8 A 0 4 1' 11 11 1' 1 11 425 1} 2A 1 II l I l l I 1 l6* 1 A 1*" '1 --11 7. 1 N16 r I 5 I I I l i I: I6 4 3:11:120;

l I I J 1 -l -l|---- I i i-" Pam-1 *E ,3; 3) b 1 il -,2 J/- l I 88 5441r I l 45; 1 E i l 1 I I It l I:

S 1 1 38 i 7 1 r 58 1! I 1 IO 1 10 r I 4-- 1 1 J 11 11 lOO US. PatentDec. 2, 1975 Sheet 2 Of8 3,923,590

Sheet 3 of 8 US. Patent Dec. 2, 1975 U.S. Patent Dec. 2, 1975 shw 5 of83,923,590

US. Patent Dec. 2, 1975 Sheet 6 of8 3,923,590

U.S. Patent Dec. 2, 1975 Sheet70f8 3,923,590

US. Patent Dec.2,1975 sheetsofs 3,923,590

DRY MOUNTING PRESS This invention relates to presses of the typecommonly called dry mounting presses which are used for the mounting ofphotographic prints, printed matter and the like by means of a heatsealing adhesive.

Usually the heat sealing adhesive is applied in the form of a heatsealing mounting .tissue which is placed between the print and the cardor substrate to which the print is to be mounted, and these componentsare bonded together under heat and pressure applied by the press.

The present invention is an improvement of dry mounting presses of thetype disclosed in U.S. Pat. No. 2644151, issued June 30, 1953 to T. H.Krueger, which employs a toggle mechanism for raising and lowering theheated platen assembly and a center shaft for transmitting pressure fromthe toggle mechanism to the platen assembly. The Krueger-type pressoffers a degree of self-adjustment of platen pressure in thefrontto-back direction, and also includes means for adjusting the platenassembly vertically so as to vary the pressure exerted on the work whenthe press is closed. Nevertheless, the Krueger-type press is limited bynonuniformity of platen pressure due to platen deflection, and suchpressure non-uniformity cannot be conviently or substantially eliminatedby the aforementioned means for vertically adjusting the platenassembly. The pressure non-uniformity is aggravated when the width ofthe press is greater than its depth. Furthermore, vertically adjustingthe platen assembly to increase or decrease the pressure exerted on theworkpiece cannot be effected suitably without first adjusting the meansthat permit the limited degree of front-to-back self-adjustment. Anotherproblem with prior dry mounting presses is non-uniformity of platentemperature due to conductive and/or radiative heat losses, notably atthe margins of the platen. Temperature differences as high as 35F havebeen found to occur due to such heat losses. Prior dry mounting presseshave other limitations known to persons skilled in the art, includingrelatively high cost.

Accordingly, the primary object of this invention is to provide amounting press which overcomes or substantially minimizes thelimitations of prior known presses.

Another object is to provide a press construction which is simple tooperate and relatively inexpensive to build.

A further object is to provide a press of the character described havingthe capability of applying pressure substantially uniformly over theentire area of the 'workpiece.

Still another object is to provide a press of the character describedhaving a novel mechanism for supporting and moving the platen assembly.

A more specific object is to provide a mounting press comprising a novelmechanism for transmitting a closing pressure to the platen assembly,said mechanism being adapted to facilitate adjustment of the closingpressure while allowing the platen assembly to be selfadjusting withrespect to front-to-back pressure.

Another specific object is to provide a press of the character describedwherein the platen assembly is selflevelling, said press comprisingmeans for transmitting a closing force to the platen assembly at aselected point or points.

Still another specific object is to provide a mechanism for supportingand moving a platen assembly characterized by means for loading theplaten assembly so as to minimize platen distortion and thus cause -amore uniform pressure distribution with respect to the work.

A further specific object is to provide means assuring a smooth floatingaction for the platen assembly when closing the press.

These and other objects which are rendered obvious hereinafter areachieved by a press of the character described wherein the platenassembly is operatively connected to the toggle mechanisms by a novelcross-bar assembly that comprises means for transmitting closingpressure to the platen assembly at selected points, said same meansbeing adapted to adjust the magnitude of said closing pressure. In otherwords, the height adjustment means doubles as a primary pressure loadingpoint or points for the platen assembly. Additionally, the platenassembly is designed to provide a more uniform temperature distributionfor the heated platen. Other features and many of the attendantadvantages of the invention are described in or rendered obvious by thefollowing description of specific embodiments of the invention which isto be considered together with the accompanying drawings wherein:

FIG. 1 is a side elevation of a preferred embodiment of the invention inthe closed position;

FIG. 2 is a plan view of the device of FIG. 1;

FIG. 3 is a side elevation showing the device of FIG. 1 in the openposition;

FIG. 4 is an enlarged fragmentary sectional view taken along line 44 ofFIG. 1;

FIG. 5 is an enlarged sectional view in elevation taken along line 5-5of FIG. 2;

FIG. 6 is an enlarged sectional view taken along line 66 of FIG. 2;

FIG. 7 is an enlarged sectional view taken along line 77 of FIG. 2;

FIG. 8 is an enlarged sectional view in elevation taken along line 8-8of FIG. 2;

FIG. 9 is a plan view, partly in section and on a reduced scale, of theheater element embodied in the platen assembly of the device of FIG. 1;

FIG. 10 is an enlarged fragmentary view taken along line 10-10 of FIG.2;

FIG. 11 is a plan view of a modification of the invention;

FIG. 12 is a sectional view in elevation taken along line 12-12 of FIG.11;

FIG. 13 is an enlarged fragmentary view taken along line 13-43 of FIG.11;

FIG. 14 is a fragmentary plan view of another modification of theinvention;

FIG. 15 is a view taken along line .l515 of FIG. 14; and

FIG. 16 is a diagram of the power and control circuit for the press ofFIG. 1.

In the drawings identical parts are referred to by the same numerals.

Referring now to FIGS. 1-3 and 8, the preferred embodiment comprises abed 2 and a platen assembly 4 which are hinged together and coupled by atoggle mechanism and cross-bar construction as hereinafter described sothat the platen assembly may be brought down against the bed as shown inFIG. 1 or raised to an open position as shown in FIG. 3, and also sothat the bonding pressure exerted by the platen assembly and bed on thework may be appropriately adjusted.

The bed 2 is a metal casting and is formed with a smooth flat surface 5which is surrounded by a marginal flange 6 so as-to provide a recess orbox-like receptacle to receive a resilient mat or body 8. The latterpreferably is made of sponge rubber or like material and has sufficientthickness so that it will project above the top edge of flange 6 toprovide for full resilient action. The bed is provided with suitablefeet 10 for resting the press on a suitable support such as a table.

The toggle mechanism comprises two identical assemblies, one at eachside of the press. Each assembly comprises a U-shaped cantilever member12 comprising a lower arm 14 and an upper arm 16. The lower arm of eachof the two members 12 is secured to the bed by means of two studs 18 and20. In this connection it is to be noted that the underside of the bedcasting is formed with a continuous flange 22 that comprises front, rearand opposite side sections that extend parallel to but are offsetinwardly of the corresponding sections of flange 6. Additionally, ateach of its opposite sides the bed casting is formed with a secondflange 24 that is spaced from the corresponding side section of flange22. The front ends of flanges 24 are connected to the side sections offlange 22 by offset portions 26, while their rear ends are integral withextensions of the rear sections of flange 22. In effect, the sidesections of flange 22 and the flanges 24 form a dual wall constructionas shown in FIG. 4. The studs 18 extend through matching holes inflanges 22 and 24 and are locked in place by C-type retaining rings 28that are engaged with grooves in the studs. Studs 20 extend throughbosses 30 formed on the underside of the bed casting and are anchored byretaining rings (not shown) in the same manner as studs 18. The feet 10are anchored in bosses formed at the four junctions of the front, rearand opposite side sections of flange 22.

Referring now to FIGS. I4 and 8, the platen assembly 4 comprises ahollow metal casting 34 having a top wall 36 with a convex curvaturefrom front to back and depending front, rear and opposite side walls 38that are straight and coact with top wall 36 to form a boxlikeenclosure. The bottom edges 40 of walls 38 are flat and lie in a commonplane. Additionally, the casting 34 has two pairs of parallel internalreinforcing ribs 42A and 42B (see FIGS. 2 and 10) that extend from frontto back and two other parallel internal reinforcing ribs 43 that extendside to side. Ribs 42A, 42B and 43 are integral with top wall 36 and thefront and rear side walls 38. The lower edges of ribs 42A, 42B and 43are spaced above the plane of the lower edges 40 of walls 38, exceptthat at their midpoints the ribs of 42A and 42B are formed with verticalextensions 45 that directly engage the platen 60 and prevent it frombowing up at its center (only the extension 45 of ribs 428 are visiblein FIG. 2). If desired, casting 34 may have additional reinforcing ribs.The two ribs 42A are each located about halfway between the center lineextending front to rear of casting 34 and the adjacent side wall 38 ofthe same casting.

The forward half of the upper wall 36 of casting 34 is formed with ahollow rectangular extension 46 that defines a small housing which isclosed off by a cover plate 48. The latter is removably secured toextension 46 by screws (not shown) and acts as a mounting plate for athermometer 50 and a thermostat light 52. A conventional bimetalthermostat 54 is mounted in the 4 platen assembly as described morefully below. The thermostat is of the type having a rotatable adjustmentshaft (not shown) which projects up through a suitable opening in coverplate 48 and'has affixed thereto a knob 56 which has a pointer thatcoacts with a temperature scale 58 provided on the cover plate toindicate the temperature setting of the thermostat. Although not shown,it is to be understood that appropriate temperature values are inscribedon cover plate 48 in association with the graduations of scale 58.Typically the scale will have a temperature range of 150 to 350F.

The platen assembly also includes a metal platen 60 having asmooth hardbottom surface. The platen is sized so that its edges are flush with theouter surfaces of the front, rear and opposite side walls 38 of theplaten assembly casting 34. Overlying and coextensive with the platen isan electrical heater unit 62. Overlying the platen is an insulatormember 64 which preferably is a relatively thick sheet of asbestos. Theremaining volume of the interior space of casting 34 may be occupied bya mass 66 of insulator wool, e.g. glas wool insulation. The platen issecured to casting 34 by means of screws 68, the latter being screwedinto tapped blind holes formed in'the platen. The margins of the heaterunit are sandwiched tightly between the platen and the bottom edges 40of walls 38. The casting and platen are both made of the same material,preferably aluminum or an aluminum alloy, so that they will have thesame coefficient of thermal expansion.

Referring now to FIG. 9, the heater unit is rectangular in area andcomprises two heater sections 70A and 70B each consisting of insulatedelectrical resistance wire 71 wound about a flat insulating core (notshown). The outer heater section 70A surrounds the inner heater section70B and each of its four legs has a width of about l-l% inches. Also,heater section 70A comprises resistance wire with a lesser resistivitythan the wire of heater section 70B. Preferably heater section 70A isdesigned to provide about twice the watt density of heater section 70B.The two heater sections may be wired for series of parallel operation(for convenience in FIG. 16, the two heater sections are considered asone). The higher heat density of heater section 70A tends tosubstantially fully offset the relatively high heat losses that occur byradiation at the edges of the platen. The two heater sections areenclosed in an insulating sheath 72. By way of example but notlimitation. the insulating core and sheath of the heater unit maycomprise a composite of mica and silicone rubber. In any event, theheater unit is made so that the sheath 72 extends beyond the edges ofthe outer heater section 70A with the result that the heater unit isbounded by an electrically insulating margin portion 74. The width ofthe latter is at least equal to and preferably slightly greater than thethickness of the walls 38. By way of example, the walls 38 may have athickness of one-eighth inch and the margin portion 74 may have a widthof about three-sixteenths inch. As a result, the intervening marginportion 74 of the heater unit is sandwiched between the lower edge ofcasting 34 and the platen and thereby tends to reduce conductive heatloss to the casting 34 from the marginal portions of the platen. Thethermostat 54 is located at the front of the platen assembly above andin engagement with the outer heater section 70A. This provides moreaccurate temperature control.

Referring now to FIGS. 1-4 and 6, the rear ends of cantilever members 12are connected by a fixed tie rod 80. Mounted on tie rod 80 so that theycan rotate but not move axially of the rod are two like bracket or hingearms 82. Axial movement of arms 82 on tie rod 80 can be prevented bymeans of retaining rings 83 secured in grooves in the tie rod. As shownin FIGS. 4 and 6, the bracket arms 82 are hollowed out so as to form achannel 86 and have solid transverse sections 84 at their front ends.Still referring to FIGS. 1-4 and 6, the toggle hinge mechanisms eachcomprise a pair of angulated toggle plates or links 88. The toggleplates are all identical and are formed so that their ends extend at anangle of about 90 to each other and define a recess at one sidecharacterized by a flat side surface 90 that faces front. As seen inFIGS. 2 and 4, each pair of toggle plates is located on opposite sidesof the upper arm 16 of one of the cantilever members 12 and the lowerends of the toggle plates are pivotally secured to the arm 16 by meansof a pivot stud 92. A C-type retaining ring 94 is mounted in a groove ineach stud so as to prevent the latter from coming out. Preferablyspacers in the form of washers 96 are located on studs 92 between thearms 16 and the toggle plates so as to facilitate pivotal movement ofthe latter.

Attached to the upper ends of toggle plates 88 is a handle mechanismthat comprises a pair of like lever arms 98 and a handle 100 whichextends between and is connected to the outer ends of the lever arms. Ifdesired, handle 100 may be connected to lever arms 98 so as to permit itto be rotated on its own axis. The opposite end of each of the leverarms 98 is provided with a lateral extension or ear 102 which is securedto the upper ends of a pair of the toggle plates 88 by a pivot stud 104.Spacers 106 like spacers 96 are interposed between arms 98 and toggleplates 88, and studs 102 are secured in place by C-type retaining rings108. Additionally the inner end of each lever arm 98 is provided with ahole located substantially along its center line to accommodate a stud110. The hole for stud 110 is located so that a line connecting it andstud 104 will be at an angle of somewhat less than 90 to the center lineof lever arm 98. Each stud 110 projects through its lever arm 98 farenough so that the surfaces 90 of both of the associated toggle platescan be engaged by the stud when the handle is moved so as to close thepress.

Studs 110 serve to connect the lever arms 98 to the bracket arms 82 andalso a metal cross beam 114. As seen best in FIGS. 77, cross-beam 114 isof U-shaped cross-section with a flat upper wall 116 and right-angledfront and rear walls 118 and 120. Additionally each end of thecross-beam has a right angled end wall 122 and an interior wall 124 thatis spaced from end wall 122 so as to define a channel 126. The rear wall120 is slotted as at 128 in line with channel 126. The front ends ofbracket arms 82 extend through slots 128 into channels 126, the latterbeing wide enough so that the bracket arms can move relative to thecross-beam. The walls 122 and 124 at each end of the cross-beams areformed with aligned holes (located substantially equidistant from frontand rear walls 118 and 120) to accommodate studs 110 which also extendthrough transverse bores formed in the solid sections 84 of bracket arms82. The portions of studs 110 that connect the cross-beam and thebracket arms have a re duced diameter so as to form a shoulder 130 (FIG.'4) that engages the outer surface of end wall 122. A C- type retainingring 132 is affixed in a suitable groove at the inner end of each stud110, the C-rings and shoulders 130 coacting with the adjacent surfacesof interior wall 124 and end wall 122 to prevent the stud from movingaxially while permitting it to rotate in those walls and the bracketarms 82.

The cross-beam 114 supports the platen assembly 4, this being achievedby connections at two spaced points. Referring now to FIGS. I3 and 5,the casting 34 of the platen assembly is formed with two bosses 134 onits upper surface, each boss being located halfway between the front andrear ends of the casting and about half-way between the front-to-rearcenter line of the casting and one of the two opposite sides. Bosses 134have flat upper surfaces and secured to each such surface by a pair ofcap screws 136 that are mounted in tapped holes in the bosses andcasting 34 is a mounting plate 138 to which is welded or swaged athreaded load-applying stud 140. Considering the platen assembly as abeam, it is preferred that the studs be located exactly half-way betweenthe front and rear ends of casting 34 and a distance from the adjacentside equal to the width of the press (which is the horizontal dimensionin FIG. 2) divided by approximately 4.5.

Screwed onto each stud 140 is an adjusting member in the form of abushing or hollow shaft 142. The latter is internally threaded so thatit can be screwed up and down on stud 140. The cylindrical outer surfaceof bushing 142 has a threaded section 144, and a reduced diameter endsection that is knurled as shown at 146 to facilitate rotation by hand.The remaining portion of its outer surface, which extends for about halfits length, is smooth except for two circumferential grooves sized toaccommodate a C-type retaining ring 148. In FIG. 5, ring 148 is shownmounted in the upper groove which is not visible but corresponds togroove 150 in the corresponding bushing 142 of FIG. 12. The second lowergroove is identified by numeral 152. Mounted on each bushing 142 is anannular dishshaped spring washer 154 of the type commonly known as aBelleville washer. The latter element rests on retaining ring 148 whichacts as a shoulder or stop. Screwed onto the threaded section 144 ofeach bushing is an adjusting nut or collar 156 which preferably has acylindrical outer surface that is knurled as shown at 158 to facilitateturning by hand. The cross-beam 114 is provided with two openings 160 inits upper wall 116, with each hole being located so as to be concentricwith one of the studs 140. Thus openings 160 are spaced from one anotherthe same amount as studs 140. Openings 160 are oversized with respect tothe bushings 142 and the upper wall 1 16 of the cross-beam is raised onboth sides around each of the openings so as to provide flat annularshoulders 162 and 164 for engagement by washer 154 and nut 156respectively.

As is obvious from the foregoing description, the studs 140, bushings142, washers 154, retaining rings 148 and nuts 156 support the platenassembly from cross-beam 114 and constitute mechanisms for adjusting theheight of the platen assembly. Also the crossbeam and hence the platenassembly are capable of rotation on a pivot axis provided by pivot studs1 10. Since the platen assembly pivot axis is located substantially atits balance point, the mechanism to the extent described will permit theplaten assembly to hang horizontal or tilt in one direction or anotherwhen the press is opened. Accordingly provision is made for limitingpivotal movement of the platen assembly. Referring now to FIGS. 4 and 6,the upper surface of the forward end of each of the bracket arms 82 isprovided with two mutually spaced depressions or cavities 166 forreceiving two resilient blocks 168 that are formed of a suitable naturalor synthetic elastomer. Preferably blocks 168 are sized so that whenseated in cavities 166 they will both lightly engage the upper wall 116of cross beam 114, i.e. they are sized so that they need not becompressed at all or to any substantial degree in order to fit as shownin FIG. 6. However, they may be made slightly oversized so that theywill be under some degree of compression when installed as in FIG. 6.The important thing is to limit free play between the crossbeam and thebracket arms in the direction of the arrow in FIG. 6, and to dampmovement of the crossbeam so that the platen assembly will not pivotfreely and instead will be inclined as shown in FIG. 3 when the press isopened. Blocks 168 may be cemented to the cross-beam or bracket arms ifdesired and also the two blocks 168 at each end of the cross-beam may beformed integral with each other.

Referring now to FIGS. 2 and 7, the cross-beam 114 also acts as ahousing and support for an ON-OFF switch 170 and an ON-OFF indicatorlight 172, both of which are mounted in its upper wall 116. Additionallyit houses a solid state relay 174 which is bolted to its rear wall 120.The latter acts as a heat sink for the relay. Switch 170 preferably isof the type having a V- shaped pivotal operating button 176, but othertypes of ON-OFF switches obviously may be used. For reasons of safety,the bottom of the cross-beam in the region of switch 170, light 172 andrelay 174 is closed off by a removable panel 178 which is secured byscrews (not shown) to the rear wall 120 of the cross-beam. As seen inFIG. 7, panel 178 also acts as point of attachment for one end of astretch-type coiled electrical cable 180 which is used to connect switch170, light 172 and relay 174 into a circuit with heater unit 62 andthermostat 54. The other end of cable 180 passes through a hole in theupper surface of platen assembly casting 34 and is connected to thethermostat and heater unit. A power cable 182, which is connected toswitch 170 and light 172, extends along the channel defined bycross-beam 114 and is bent rearward so as to extend along the channel 86,of the right-hand bracket member 82 as seen in FIG. 2. The power cableextends out of the rear end of the bracket arm and is provided withsufficient length for its free end to be conveniently plugged into aconventional wall outlet. Small brackets (not shown) are used to holdcable 182 close against the cross-beam and bracket arm for reasons ofsafety and appearance.

FIG. 16 shows the electrical control circuit for the above describedpress. The heater unit 62, ON-OFF switch 170 and relay 174 are connectedin series between two input terminals 186 which are connected by powercable 182 to a suitable AC. power source. The relay 174 comprises atriac having its T and T terminals connected in series with switch 170and heater unit 62, while its gate electrode is connected through asuitable biasing resistor 184 and thermostat switch 54. The thermostatlight 52 is connected across the heater unit while the power ON light172 is connected in series with switch 170. With this unit, closing ofthe thermostat switch causes the triac to conduct and thereby causeheater 62 and light 52 to be energized. It is to be noted that themagnitude of the current carried by the thermostat is relatively low,the heavy current load for the heater being carried by the triac ratherthan the thermostat. By way of example, 8 to amperes are carried by theheater unit while only a to 1% ampere signal is passed by thethermostat. This has the effect of materially prolonging thermostatlife.

These are the advantages of the press described above. For one thing,when the handle is moved backward to the position of FIG. 3, the platenassembly is raised as a consequence of the pivot axis of the crossbeam,i.e. studs 110, being swung upwardly (clockwise in FIG. 1) about theaxis provided by studs 104. As seen in FIG. 3, the extent of rearwardmovement of handle is limited by its engagement with the upper surfacesof the rear ends of bracket arms 82. When the handle is moved forwardagain (FIG. 2) reverse operation occurs and the platen assembly islowered to close the press. The toggle plates undergo limited movementon the pivot studs 92 when the platen assembly is raised and lowered.When the platen assembly is lowered to close the press it can be lockedin the closed position by the sample expedient of forcing the handledown far enough to locate the axis of pivot studs rearwardly of the linejoining the axes of pivot studs 92 and 104. In other words the press isheld closed by virtue of the overcentering of pivot studs 110. When thepress is locked in the closed position, studs 1 10 engage surfaces 90 oftoggle plates 88. A similar overcentering action holds the press open.In this connection note that in FIG. 3 the pivot studs are again to oneside of a line joining the axes of pivot studs 92 and 104. On closingthe press, the resilient blocks 168 permit the platen assembly to pivotrelative to bracket arms 82 so as to automatically level itself whenpressed against the bed.

The cross-beam 114 and the height adjusting mechanisms (elements 140,142, etc.) constitute the means for transmitting closing pressure to theplaten assembly from the toggle mechanisms. The toggle mechanism doesnot apply closing pressure to the platen assembly through tie-rod 80 andbracket arms 82. As a consequence the hinge construction provided by tierod 80 and bracket arms 82 need not be heavy. Adjustment of the pressureexerted on the work by the press is achieved by backing off nuts 156 andthen screwing bushings 142 up or down on studs so as to lower or raisethe platen assembly relative to cross-beam 114. The two bushings areturned so that equal pressure is exerted by the cross-beam on both studs140. Once the correct pressure is achieved, the nuts 156 are tightenedup enough so as to lock the bushings against rotation. The heightadjusting mechanisms permit the platen pressure to be adjusted correctlyfor laminating as well as dry-mounting. Also the height adjustmentmechanisms allow the press to accept relatively thick as well asrelatively thin work-pieces so that, for example, the press may be usedto dry-mount a print to a r-inch substrate. Typically the threadedsections 144 of bushings 142 are long enough to permit a 1 inch heightadjustment for the platen assembly. The two grooves and 152 in thebushings allow the same height adjustment units to be used in differentsize presses. A particular advantage of the height adjustment capabilityof the press is that the height of the platen assembly can be variedwithout having to adjust any other mechanism. The most importantadvantage of the invention is that use of the cross-beam permits loadingthe press so as to reduce the variations in pressure along the full areaof the platen to less than 1 psi, which is a marked improvement over theKrueger-type press which typically has a pressure variation of 3 psi andgreater. The remaining deflection of about 1 psi or less is due todeflection of the bed and manufacturing tolerances. It has been foundthat the optimum loading points are those which produce minimum platendeflection across the width of the press, and those have been found tobe at distances from the sides of the platen assembly equal to thelatters width divided by about 4.5.

The cross-beam construction can be expanded to permit loading at morethan two points for optimization of platen loading. This modification ofthe invention is shown in FIGS. 14 and 15. In this case the cross-beam114 is provided with two pairs of front and rear extensions 190 and192., and each extension is provided with an opening corresponding toopening 160 for accomodating a height adjustment unit like that shown inFIG. 5. The platen casting 34 is formed with a two elongate bosses 134Aand two threaded studs 140 are secured to each boss. The rear studs 140are located so as to be spaced from the rear end of the platen assemblya distance equal to the depth of the platen assembly divided byapproximately 4.5 and the front studs are spaced the same distance fromthe front end of the assembly. The studs 140 on the left of FIG. 14 arespaced from the left hand side of the platen assembly a distance equalto the width of the assembly divided by 4.5 and the right-hand studs 140are correspondingly spaced from the right hand side of the platenassembly. With this arrangement, loading forces are transmitted from thecross-beam to the platen assembly at four distinct points. Thismodification produces a better pressure distribution on the workpiecethan the device of FIG. 1, but is more expensive to manufacture.

The cross-bar loading arrangement also may be modified so as to transmitthe loading force to the platen assembly at a single point. Thismodification of the invention, which is shown in FIGS. 11-13, isadvantageous for relatively small size presses which usually have lessof a platen deflection problem.

Referring now to FIG. 11-13, the cross-beam 1 14 has a single opening160 located equidistance from its opposite ends for accomodating abushing 142, and the platen assembly casting 34 has a single boss 134Blocated at its centerpoint to which is attached the threaded stud 140 onwhich the bushing is mounted. FIG. 12 illustrates the retaining ring 148for the spring washer 154 mounted in the lower groove 152 of thebushing. As is obvious, since only a single height adjustment unitconnects the platen assembly to the crossbeam, the platen assembly willtend to rotate about the axis of bushing 142 when the lock nut 156 isloosened. Therefore, means are provided is prevent such rotation so asto assure that the sides of the platen will line up with the sides ofthe bed when the press is closed. The means for restraining the platenassembly against rotation comprises two bosses 194 formed on the uppersurface of platen casting 34 adjacent each side and behind itsside-to-side center line, plus two rear extensions 196 on the cross-beamwhich are aligned with bosses 194. Extensions 196 have cavities 198 onthe bottom sides. Secured to the upper end of each boss 194 by a screw200 is a rubber plug 202. Plugs 202 extend up into cavities 198 andcoact with the surrounding surfaces of extensions 196 to prevent theplaten assembly from rotating on the axis of bushing 142. Obviously onlyone extension 196, one boss 194 and one rubber plug 202 are required toprevent rotative movement of the platen assembly, but the dualarrangement shown in FIG. 11 is preferred for reasons of symmetry. Asshown in FIGS. 11 and 13, the bracket arms 82 are spaced inwardly of thesides of the press far enough to permit the provision of extensions 196on the crossbeam. For this purpose it is preferred that the crossbeam beformed with an additional internal wall 127 (FIG; 13) at each end formounting the studs 110. The rear wall of the cross-beam is slottedbetween walls 124 and 127 as shown at 129 for accommodating the forwardends of bracket arms 82.

Except as may be otherwise noted above, the modifications of FIGS. 11-13and FIGS. 14 and 15 are constructed and operate in the same manner asthe preferred embodiment of FIGS. l-10 and 16.

It is recognized that still other changes may be made without departingfrom the principles of the invention.

What is claimed is:

1. A press comprising:

a bed;

a platen assembly positioned above said bed;

hinge arms pivotally connected to the bed;

a cross-beam extending transversely of said hinge arms over said platenassembly; pivot means connecting said hinge arms to said crossbeam so asto allow relative pivotal movement between said cross-beam and saidhinge arms;

height-adjusting means located between and spaced from said hinge armsfor locking said platen assembly to said cross-beam;

toggle links pivotally connected to opposite sides of said bed;

lever arms pivotally connected to said toggle links;

means connecting said cross-beam to said lever arms;

and

means for pivoting said lever arms relative to said toggle links so asto selectively raise and lower said platen assembly into open and closedpositions respectively relative to said bed; said height adjusting meanscomprising a stud affixed at one end to said platen assembly, androtatable threaded means screwed onto said stud connecting saidcross-beam to said stud, whereby the spacing between said cross-beam andsaid platen assembly can be varied by rotating said threaded means onsaid stud.

2. A press according to claim 1 wherein said rotatable threaded meanscomprises a nut and a bushing with interior and exterior screw threads,said bushing being screwed onto said stud and extending up through anoversized hole in said crossbeam, said bushing having a flange engagingthe underside of said cross-beams said nut'being screwed onto saidbushing and coacting with the upper side of said cross-beam whereby tolock said bushing against rotation on said stud.

3. A press according to claim 2 wherein said flange is a spring washerremovably mounted on said bushing.

4. A press according to claim 3 including means on said bushingproviding a shoulder for engaging said spring washer and holding itagainst said cross-beam.

5. A press according to claim 1 wherein said stud and the said hole insaid cross-bearn are located substantially half-way between the oppositeends of said crossbeam.

6. A press according to claim 5 further including cooperating meanscarried by said cross-beam and said platen assembly for preventingrotation of said platen assembly and stud relative to said cross-beam.

7. A press according to claim 1 including a second like height-adjustingmeans connecting said platen assembly to said cross-beam, saidfirst-mentioned heightadjusting means having its stud locatedintermediate one end and the midpoint of said cross-beam and said secondheight-adjusting means having its stud located intermediate the oppositeend and the midpoint of said cross-beam.

8. A press according to claim 2 including a second like height-adjustingmeans connecting said platen assembly to said cross-beam, saidfirst-mentioned heightadjusting means having its bushing extending upthrough a hole in said cross-beam which is located between one end andthe midpoint of said cross-beam and said second height-adjusting meanshaving its bushing extending up through a hole in said cross-beamlocated intermediate the opposite end and the midpoint of saidcross-beam.

9. A press according to claim 8 wherein said holes are located at equaldistances from said midpoint 10. A press according to claim 2 whereinthe upper end of said bushing is adapted for turning said bushing onsaid stud.

11. A press according to claim 1 comprising four of saidheight-adjusting means connecting said platen assembly to saidcross-beam, first and second ones of said height-adjusting means beinglocated at one side of said cross-beam and the third and fourth ones ofsaid height-adjusting means being located at another side of saidcross-beam, said first and third height-adjusting means being disposedon one side of and spaced equidistant from a line intersecting themidpoint of said cross-beam at a right angle and said second and fourthheight-adjusting means being disposed on the opposite side of and spacedequidistant from said intersecting line, with said line beingequidistant from said first and second height-adjusting means.

12. A press according to claim 1 further including resilient meansinterposed between said cross-beam and at least one of said hinge armsfor limiting relative movement between said cross-beam and said hingearms.

13. A press comprising:

a bed;

a platen assembly located above the bed;

first and second hinge arms pivotally connected to the bed at oppositesides thereof;

a cross-beam extending transversely of said hinge arms over said platenassembly;

height-adjusting means located between and separate from said hinge armsfor connecting said platen assembly to said cross-beam, saidheight-adjusting means comprising a threaded stud affixed to said platenassembly and threaded means screwed into said stud for connecting saidstud to said cr'ossbeam so that said platen assembly will move up anddown with said cross-beam;

first and second toggle links;

first and second pivot studs pivotally connecting one end of said firstand second toggle links respectively to said opposite sides of said bed;

first and second lever arms at said opposite sides of said platenassembly;

third and fourth pivot studs pivotally connecting the other ends of saidfirst and second toggle links to said first and second lever armsrespectively;

fifth and sixth pivot studs each mounted to an opposite end of saidcross-beam, said fifth pivot stud being connected to said first hingearm and said first lever arm and said sixth pivot stud being connectedto said second hinge arm and said second lever arm so as to allowrelative pivotal movement among said cross-beam, said hinge arms andsaid lever arms; and

means connecting said lever arms for pivoting said lever arms relativeto said toggle links so as to selectively raise and lower said platenassembly into open and closed positions respectively relative to saidbed,

each of said toggle links being angulated and having a recess along oneside thereof between its two pivots, said toggle links and said fifthand sixth studs being disposed so that portions of said fifth and sixthstuds can move into said recesses to an overcentered relation with saidfirst and second toggle links respectively when said platen assembly ismoved into its said closed position by pivotal movement of said leverarms.

14. A press according to claim 13 including third and fourth togglelinks,

said first and third toggle links being disposed on 0pposite sides ofsaid first lever arm and said second and fourth toggle links beingdisposed on opposite sides of said second lever arm, said third andfourth toggle links being pivotally mounted at one end to said first andsecond pivot studs respectively and pivotally mounted at the oppositeend to said third and fourth studs respectively, said fifth and sixthpivot studs extending in front of said third and fourth toggle linksbetween said lever arm and said cross-beam.

1. A PRESS COMPRISING: A BED; A PLATEN ASSEMBLY POSITIONED ABOVE SAIDBED; HINGE ARMS PIVOTALLY CONNECTED TO THE BED; A CROSS-BEAM EXTENDINGTRANSVERSELY OF SAID HINGE ARMS OVER SAID PLATEN ASSEMBLY; PIVOT MEANSCONNECTING SAID HINGE ARMS TO SAID CROSS-BEAM SO AS TO ALLOW RELATIVEPIVOTAL MOVEMENT BETWEEN SAID CROSS-BEAM AND SAID HINGE ARMS;HEIGHT-ADJUSTING MEANS LOCATED BETWEEN AND SPACED FROM SAID HINGE ARMSFOR LOCKING SAID PLATEN ASSEMBLY TO SAID CROSS-BEAM; TOGGLE LINKSPIVOTALLY CONNECTED TO OPPOSITE SIDES OF SAID BED; LEVER ARMS PIVOTALLYCONNECTED TO SAID TOGGLE LINKS; MEANS CONNECTING SAID CROSS-BEAM TO SAIDLEVER ARMS; AND MEANS FOR PIVOTING SAID LEVER ARMS RELATIVE TO SAIDTOGGLE LINKS SO AS TO SELECTIVELY RAISE AND LOWER SAID PLATEN ASSEMBLYINTO OPEN AND CLOSED POSITIONS RESPECTIVELY RELA-
 2. A press accordingto claim 1 wherein said rotatable threaded means comprises a nut and abushing with interior and exterior screw threads, said bushing beingscrewed onto said stud and extending up through an oversized hole insaid crossbeam, said bushing having a flange engaging the underside ofsaid cross-beams said nut being screwed onto said bushing and coactingwith the upper side of said cross-beam whereby to lock said bushingagainst rotation on said stud.
 3. A press according to claim 2 whereinsaid flange is a spring washer removably mounted on said bushing.
 4. Apress according to claim 3 including means on said bushing providing ashoulder for engaging said spring washer and holding it against saidcross-beam.
 5. A press according to claim 1 wherein said stud and thesaid hole in said cross-beam are located substantially half-way betweenthe opposite ends of said cross-beam.
 6. A Press according to claim 5further including cooperating means carried by said cross-beam and saidplaten assembly for preventing rotation of said platen assembly and studrelative to said cross-beam.
 7. A press according to claim 1 including asecond like height-adjusting means connecting said platen assembly tosaid cross-beam, said first-mentioned height-adjusting means having itsstud located intermediate one end and the midpoint of said cross-beamand said second height-adjusting means having its stud locatedintermediate the opposite end and the midpoint of said cross-beam.
 8. Apress according to claim 2 including a second like height-adjustingmeans connecting said platen assembly to said cross-beam, saidfirst-mentioned height-adjusting means having its bushing extending upthrough a hole in said cross-beam which is located between one end andthe midpoint of said cross-beam and said second height-adjusting meanshaving its bushing extending up through a hole in said cross-beamlocated intermediate the opposite end and the midpoint of saidcross-beam.
 9. A press according to claim 8 wherein said holes arelocated at equal distances from said midpoint.
 10. A press according toclaim 2 wherein the upper end of said bushing is adapted for turningsaid bushing on said stud.
 11. A press according to claim 1 comprisingfour of said height-adjusting means connecting said platen assembly tosaid cross-beam, first and second ones of said height-adjusting meansbeing located at one side of said cross-beam and the third and fourthones of said height-adjusting means being located at another side ofsaid cross-beam, said first and third height-adjusting means beingdisposed on one side of and spaced equidistant from a line intersectingthe midpoint of said cross-beam at a right angle and said second andfourth height-adjusting means being disposed on the opposite side of andspaced equidistant from said intersecting line, with said line beingequidistant from said first and second height-adjusting means.
 12. Apress according to claim 1 further including resilient means interposedbetween said cross-beam and at least one of said hinge arms for limitingrelative movement between said cross-beam and said hinge arms.
 13. Apress comprising: a bed; a platen assembly located above the bed; firstand second hinge arms pivotally connected to the bed at opposite sidesthereof; a cross-beam extending transversely of said hinge arms oversaid platen assembly; height-adjusting means located between andseparate from said hinge arms for connecting said platen assembly tosaid cross-beam, said height-adjusting means comprising a threaded studaffixed to said platen assembly and threaded means screwed into saidstud for connecting said stud to said cross-beam so that said platenassembly will move up and down with said cross-beam; first and secondtoggle links; first and second pivot studs pivotally connecting one endof said first and second toggle links respectively to said oppositesides of said bed; first and second lever arms at said opposite sides ofsaid platen assembly; third and fourth pivot studs pivotally connectingthe other ends of said first and second toggle links to said first andsecond lever arms respectively; fifth and sixth pivot studs each mountedto an opposite end of said cross-beam, said fifth pivot stud beingconnected to said first hinge arm and said first lever arm and saidsixth pivot stud being connected to said second hinge arm and saidsecond lever arm so as to allow relative pivotal movement among saidcross-beam, said hinge arms and said lever arms; and means connectingsaid lever arms for pivoting said lever arms relative to said togglelinks so as to selectively raise and lower said platen assembly intoopen and closed positions respectively relative to said bed, each ofsaid toggle links being angulated and having a recess along one sidethereof between its two pivots, Said toggle links and said fifth andsixth studs being disposed so that portions of said fifth and sixthstuds can move into said recesses to an overcentered relation with saidfirst and second toggle links respectively when said platen assembly ismoved into its said closed position by pivotal movement of said leverarms.
 14. A press according to claim 13 including third and fourthtoggle links, said first and third toggle links being disposed onopposite sides of said first lever arm and said second and fourth togglelinks being disposed on opposite sides of said second lever arm, saidthird and fourth toggle links being pivotally mounted at one end to saidfirst and second pivot studs respectively and pivotally mounted at theopposite end to said third and fourth studs respectively, said fifth andsixth pivot studs extending in front of said third and fourth togglelinks between said lever arm and said cross-beam.